XNC Format: Gerber Takes Data Into the Future


Reading time ( words)

Gerber is the world’s favourite data exchange format for PCB image data: it’s easy to use, crystal clear, and gives designers and engineers an unequivocal language with which to communicate with each other. And this grand old man of the PCB industry has remained at the forefront, powered by ongoing developments that add capability and functionality without ever compromising its characteristic simplicity and ease of use.

It’s the ideal solution for transferring drill data too, as can be seen from scanning the specification. And many in the PCB industry use it for just this, but the majority are still transferring their routing and drilling coordinates using NC formats. These were never designed for data transfer, and more often than not create confusion and waste time.

Some argue that Gerber files, unlike NC files, can’t be sent to a drilling machine. True enough, but PCB manufacturers never send their clients’ incoming files to their machines anyway. Instead, the data goes through the CAM process and is then altered and output as is appropriate to the manufacturer’s specific production line. For CAD, the question should not be which format is best for the machines, but rather which format is best for input into CAM. As we’ve said, this is undoubtedly Gerber.

So, why are CAD developers and their users still stuck on NC formats? It’s most likely a question of inertia or tradition. Drill information has been transferred for decades using NC formats, principally Excellon (hence the generic use of the name “Excellon” for “NC files”), that are similar to the 1985 IPC-NC349 specification. Also, there’s still a lot of legacy software out there, so NC files will likely be with us for a while.

The Problem With Existing NC Specifications

The problem is that so many NC files are of deplorable quality because the NC format was never designed as a data transfer format. It has always been a machine driver and contains all sorts of information that a drilling machine needs, but that is irrelevant and confusing for data exchange. For example, CAD software will typically ask users to specify whether routing should be achieved using nibbling or slot creation and which drill feeds and speeds are to be used. These are decisions that only the fabricator can make, and yet many CAD professionals will feel duty bound to give some sort of answer, which will inevitably be wrong.

To read this entire article, which appeared in the April 2019 issue of Design007 Magazine, click here.

Share

Print


Suggested Items

Turning ‘Garbage In, Garbage Out' into ‘Good In, Good Out’

03/23/2021 | Tamara Jovanovic, Happiest Baby
In the PCB design cycle, it is so easy to unintentionally introduce “garbage” into your system. Unless you have time to extensively check everything you bring in from an external source, it is very likely that something will not match up with your design data. In the end, this means you’ll have to put more work into your design and basically reverse-engineer a part that was supposed to save you time and effort.

Karen McConnell: Recipient of the IPC Raymond E. Pritchard Hall of Fame Award

03/11/2021 | Patty Goldman, I-Connect007
"I heard about IPC when I started a new job at UNISYS after graduating college. I moved from ASIC design to printed circuit boards," said Karen McConnell after being inducted into the Raymond E. Pritchard Hall of Fame. "At the time, in the late ’80s and early ’90s, there were rumors going around that printed circuit boards were going to disappear, and ASICs were going to take over the world. But something in printed circuit boards fascinated me. I minored in robotics in college as an electrical engineer and the data used to fabricate, assemble and test the boards is actually all robotic language. I was hooked."

The Key to Eliminating Bad Design Data: Constant Vigilance

03/09/2021 | I-Connect007 Editorial Team
The I-Connect007 editorial team recently met with Jen Kolar and Mark Thompson of Monsoon Solutions to discuss ways to eliminate bad data from the design process, whether that be from CAD libraries, parts vendors, chip makers, or customers themselves. They key in on some problems and obstacles that allow incorrect data into the design cycle, and then highlight possible solutions.



Copyright © 2021 I-Connect007. All rights reserved.